Ford had been keeping the full event of its range-topping 2021 Mustang Mach-E GT’s performance under wraps, but now we know that the all-electric crossover really is worthy of pony car club membership. Announced alongside the rest of the Mustang Mach-E range last year, though not arriving in dealerships until spring 2021, the GT packs 459 horsepower and 612 lb-ft …